Electronic clocking circuits are used in a wide variety of applications. For example, many solid state electronic devices (e.g., microprocessors) operate at a rate set by an internal or external clocking circuit. Accordingly, the accuracy of the clocking signal generated by a clocking circuit generally is critical to the proper operation of the underlying device being clocked. Many devices thus use conventional crystal oscillators to clock their underlying processes.
Crystal oscillators, however, have a number of drawbacks. For example, stable crystal oscillators typically are relatively large and expensive. Microelectromechanical systems (MEMS) resonators show promise in replacing crystal oscillators as well as filters such as Surface Acoustic Wave (SAW) and Bulk Acoustic Wave (BAW) filters used in communications devices. However, due to processing conditions, some MEMS resonators may be asymmetric, causing variation in resonator resonant frequency that may vary across a wafer or from different production lots.